I'm trying to connect a 1/4" or 3/8" reverse osmosis tubing to a 3/8" compression fitting. I've bought multiple connectors but no luck - any recommendations on what I should look for?

This is for https://media.deltafaucet.com/SpecSheet/DSP-K-1930-DST%20Rev%20A.pdf

(the flexibility in RO tubing size is because I have a reducer)

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2 Answers 2


I believe you can you a compression fitting coupler, such as this product: Home Depot link. enter image description here

You should be able to simply unscrew the end fittings and attach your existing compression fittings.

  • I bought this and it connects to the spigot hose I posted the picture of which is very helpful. I was able to insert the 3/8" tube into the other end of it and tighten it, but it doesn't seem to grip the tube such that it can't come out. Any ideas on what I'm doing wrong or what else I need to buy? Thanks
    – g491
    Oct 2, 2021 at 18:05
  • Perhaps I need a compression ring / ferrule / fitting that it didn't come with?
    – g491
    Oct 2, 2021 at 18:15

Sounds like you're looking for the tube insert to transition from plastic to brass.


This one is available in 1/4 and 3/8 sizes.

  • Thanks - I think that's exactly what else I need
    – g491
    Oct 2, 2021 at 21:08

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